Considerations for the implementation of the radio interferometric positioning system on a single wireless node

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Abstract

The ability to localise objects and persons is a useful ability, that is currently used in everyday
life in the form of Global Positioning System (GPS) navigation. Localisation is
also useful in data networks. The ability to localise nodes in a network paves the way
for applications such as location based services, beamforming and geographic routing.
The Radio Interferometric Positioning System (RIPS), is a method originally designed
for localisation in wireless sensor networks. RIPS is a promising method due to the fact
that it is capable of localisation with high accuracy over long ranges. This is something
which other existing methods are not capable of.
RIPS makes localisation measurements in a different manner from conventional methods.
Instead of making pairwise measurements between a transmitter and receiver,
RIPS uses sets of four nodes in each of its measurements. Furthermore, RIPS requires
multiple measurements to obtain the correct RIPS measurement value. This value is
referred to as a q–range. Multiple q–ranges are required in order to localise a node.
This creates overhead in terms of co–operation between the nodes participating in a
RIPS measurement.
The focus of this research is to provide a possible solution to this problem of overhead.
In this dissertation an investigation is launched into the considerations and benefits
of implementing RIPS on a single node. This is done by creating a conceptual design
for a single wireless node capable of implementing RIPS through the use of multiple
antennas. In order to test this conceptual device, a simulation model is created.
This simulation model is then validated, verified and used in experiments designed
to test the effects of certain design considerations and variables on the conceptual device’s
localisation accuracy. The analysis of the results from these experiments shows
that the conceptual device’s use of multiple antennas makes RIPS sensitive to errors.
Increasing the distances separating the conceptual device’s antennas is found to decrease
this sensitivity to errors. This is shown to be caused by the distances separating
the antennas imposing limits on the range of q–ranges values that are possible, with
smaller distances resulting in smaller ranges of possible q–range values. It is also found
that the use of higher frequencies in RIPS measurements results in greater accuracy.
This is with the assumption that these frequencies can be accurately transmitted.